High Pressure Fitting

ABSTRACT

A fitting, such as an anti-blowback fitting, that includes a friction reducing device that enables easy removal of the fitting from a high pressure connection such as one associated with an HVAC unit. When used in connection with refrigeration, anti-blow back fittings function to keep the refrigerant in the hose to which it is connected in order to minimize or prevent the refrigerant from escaping to the environment. In certain embodiments, a friction reducing device is positioned in the fitting, and decreases the load on the rear housing, which enables easy rotation of the outer or swivel housing of the fitting to remove the same from the high pressure connection. In certain embodiments, the friction reducing device is a thrust bearing.

BACKGROUND

Mechanical air conditioning and refrigeration are accomplished bycontinuously circulating, evaporating, and condensing a fixed supply ofrefrigerant in a closed system. Charging or recharging an airconditioning or refrigeration system with refrigerant is done throughthe low side suction intake fitting with the use of manifold gauges andservice hoses. There are several types of refrigerants used and some canbe charged as a vapor and others must be charged as a liquid.

For example, R-410A is replacing R-22 refrigerant and is a mixture ofHFC-32 and HFC-125, and is thus considered to be zeotropic. Zeotropicrefrigerants such as R-410A must be charged as a liquid from a canisterdue to the possibility of fractionation of the blend of refrigerants itcontains. The range of temperatures at which components in the blendedcomponents of R-410A refrigerant boil (temperature glide) is <0.3° F.,making it a near-azeotropic refrigerant mixture.

Since the different components of zeotropic refrigerants such as R-410Ahave different boiling points, the components fractionate duringboiling. That is, as the temperature increases, the lower boiling pointcomponents vaporize first. The vapor thus has a higher concentration ofthe lower boiling components than the liquid, and a lower concentrationof the higher boiling components. When such a fluid blend is stored in aclosed container in which there is a vapor space above the liquid, thecomposition of the vapor is different from the composition of theliquid. If the fluid is then removed from the container to charge an airconditioning system, for example, fractionation can take place, withaccompanying changes in composition. Such changes can cause arefrigerant to have a composition outside of specified limits, to havedifferent performance properties or even to become hazardous, such as bybecoming flammable.

In general, R-410A pressures are 1.8 times higher than those of R-22,and can be over 600 psi. CO₂ is an example of another refrigerant gasthat can run at a much higher pressure, as high as 1800 psi or more.

Low-pressure vapor refrigerant is compressed and discharged from thecompressor as a high temperature, high-pressure, “superheated” vapor orliquid. The high-pressure refrigerant flows to the condenser, where itis changed to a low temperature, high-pressure liquid. It then flowsthrough a filter dryer to a thermal expansion valve or TXV. The TXVmeters the correct amount of liquid refrigerant into an evaporator. Asthe TXV meters the refrigerant, the high-pressure liquid changes to alow pressure, low temperature, saturated liquid/vapor. This saturatedliquid/vapor enters the evaporator and is changed to a low pressure, dryvapor. The low pressure, dry vapor is then returned to the compressor.The cycle then repeats.

Because of the relatively high pressures involved, difficulties havearisen in removing fittings, such as anti-blowback fittings, coupled tohigh pressure, such as the hose connecting the high side of arefrigeration unit to the refrigerant source. The high pressure putsforce on the connection, making it difficult to remove the fitting,especially manually.

It therefore would be desirable to provide a fitting that is easilyremoved from a high-pressure connection. It would be particularlydesirable to provide a fitting that is easily removed from ahigh-pressure connection manually, i.e., without the need for a tool toapply torque to the fitting greater than can be applied by hand.

SUMMARY

The shortcomings of the prior art have been overcome by the embodimentsdisclosed herein, which relate to a fitting, such as an anti-blowbackfitting, that includes a friction reducing device that enables easyremoval of the fitting from a high-pressure connection such as thatassociated with an HVAC unit. When used in connection withrefrigeration, anti-blow back fittings function to keep the refrigerantin the hose to which it is connected in order to minimize or prevent therefrigerant from escaping to the environment.

In certain embodiments, a friction reducing device is positioned in thefitting, and enables easy rotation of the outer housing of the fittingdespite the axial load resulting from the high pressure connection, toremove the same from the high-pressure connection by hand and withoutthe need for tools to supply sufficient torque.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a fitting in accordance with certainembodiments;

FIG. 2 is a cross-sectional view of the fitting of FIG. 1 in accordancewith certain embodiments;

FIG. 3 is a cross-sectional view of a swivel housing in accordance withcertain embodiments;

FIG. 4 is a cross-sectional view of a front housing in accordance withcertain embodiments;

FIG. 5A is a cross-sectional view of a depressor in accordance withcertain embodiments;

FIG. 5B is a top view of the depressor of FIG. 5A;

FIG. 6 is a cross-sectional view of a rear housing in accordance withcertain embodiments;

FIG. 7 is a cross-sectional view of a friction reducing device inaccordance with certain embodiments;

FIG. 8 is a cross-sectional view of a retaining member in accordancewith certain embodiments;

FIG. 9 is an exploded view of a fitting in accordance with anotherembodiment;

FIG. 10 is a cross-sectional view of the fitting of FIG. 9;

FIG. 11 is an exploded view of a fitting in accordance with yet anotherembodiment; and

FIG. 12 is a cross-sectional view of the fitting of FIG. 11.

DETAILED DESCRIPTION

Turning first to FIGS. 1 and 2, there is shown a fitting 10, which inthe embodiment shown, is an anti-blowback fitting. In accordance withcertain embodiments, the fitting 10 includes an outer or swivel housing12, front housing 14, depressor 16, biasing member 18, rear housing 20,friction reducing device 22, and retaining member 24.

As best seen in FIG. 3, in accordance with certain embodiments theswivel housing 12 is generally cylindrical, and includes an internalcavity 28. The distal end 12A of the swivel housing 12 has a centralbore 30 that is internally threaded so that it can mate with acorresponding threaded male member on the HVAC unit (not shown) toconnect the fitting to the unit. The central bore 30 is in fluidcommunication with the internal cavity 28, and has an inner diameterless than the inner diameter of the central bore 30. Near the proximalend 12B of the swivel housing 12 there is formed an internal annulargroove 29 to receive retaining member 24 as discussed in greater detailbelow. In certain embodiments, the internal cavity 28 houses the fronthousing 14, the depressor 16, the biasing member 18, a portion of therear housing 20, the friction reducing device 22, and the retainingmember 24.

In accordance with certain embodiments, FIG. 4 shows a front housing 14that is generally cylindrical and has an outer diameter smaller than theinner diameter of the swivel housing 12 so that the front housing 14fits inside the swivel housing 12, as seen in FIG. 2. In certainembodiments, the housing 14 includes a distal end 35A having a regionwith internal threads 31, and a proximal end 35B with flanges 14A, 14Bthat extend radially inwardly from the end as shown. The flanges 14A,14B retain O-ring 65 as seen in FIG. 2. An intermediate region includesflange members 14C, 14D, each having a main body that extends radiallyinwardly. Leg 14E extends axially from the main body of flange 14C inthe direction of the distal end 35A, and leg 14F extends axially fromthe main body of flange 14D in the direction of the distal end 35A.

In accordance with certain embodiments, FIGS. 5A and 5B show a depressor16 that is configured to be positioned inside the front housing 14 asshown in FIG. 2. The depressor 16 has a main body 41 that terminates atone end with a central axially extending member 42. The main body 41sits on a hollow hexagonal base 43 as seen in FIG. 5B. When positionedin the front housing 14, the outer wall of the main body 41 abuts theouter walls of the flange members 14C, 14D and legs 14E, 14F of theouter housing 14, and a square seal 75 is positioned on the shoulder 44and free distal end 55 of the rear housing 20. (FIG. 2). The depressor16 is normally urged axially towards the distal end 30 of the swivelhousing 12 by biasing member 18 that seats within the hollow region ofthe hexagonal base 43, as best seen in FIG. 2. When the force of thebiasing member 18 is overcome such as by connection of the fitting to ahigh pressure unit, the depressor is forced axially away from the distalend 12A of the housing 12.

In accordance with certain embodiments, FIG. 6 shows a rear housing 20.The housing 20 includes at the distal end 54 an axially extending ring51 having external threads 58 that mate with internal threads 31 in thefront housing 14. Extending axially from the ring 51 is a main bodymember 55, which seats the biasing member 18 (FIG. 2) and extendsradially outwardly a distance greater than the diameter of the ring 51.In certain embodiments, the opposite proximal end of the housing 20 isan elongated barbed member 52 formed with a plurality of barbs 53A, 53B,53C. Each barb is frusto conical in shape, tapering radially outwardlyas it extends axially towards the distal end 54. The barb member 52receives a hose (not shown) or the like. The barb member 52 includes anelongated leg 56 that connects the barbed portion to the main bodymember 55. The elongated leg 56 includes a region 57 of increaseddiameter 58 that is surrounded by friction reducing device 22 when inthe assembled condition (FIG. 2). The barbs on the housing 20 are notnecessary; connection can be made to the housing 20 by other suitablemeans, such as threads or a quick coupler.

In accordance with certain embodiments, FIG. 7 illustrates an embodimentof the friction reducing device 22. In the embodiment shown, thefriction reducing device 22 is a thrust bearing that is a rotary typebearing that permits rotation between parts, while supporting an axialload. In accordance with certain embodiments, the thrust bearingincludes outer washers 61, 62 that sandwich an inner cage 63. Thewashers 61, 62 may be made of stainless steel or other suitablematerial, and the inner cage 63 of nylon or metal, for example. Thewashers 61, 62 and inner cage 63 each has a central bore 66 that alignwhen in the assembled condition. The inner cage 63 has a plurality ofapertures, each receiving a ball bearing 64 held in place by the outerwashers 61, 62. Although a thrust ball bearing is illustrated, thoseskilled in the art will appreciate that other types of friction reducersmay be used, such as thrust roller bearings, slip washers or plates, orother known friction reducing members as discussed in greater detailbelow. The slip washers or plates can be made of or coated withpolytetrafluoroethylene (Teflon®) or the like, for example. The frictionreducing device 22 is positioned in the swivel housing 12 such that itabuts against the rear wall of the main body member 55 of the rearhousing 20, and the region 57 of the main body member 55 is received inthe central bore 66 of the device 22, as best seen in FIG. 2. Theupstream outer washer 62 rotates with the swivel housing 12, while thedownstream outer washer 61 does not. This reduces friction betweenswivel housing 12, rear housing 20 and retaining member 24, and allowsfor manual rotation of the swivel housing despite the axial load causedby the high pressure connection.

In accordance with certain embodiments, FIG. 8 shows a retaining member24. The retaining member 24 is resilient, preferably made of steel, andis force fit into annular groove in the swivel housing 12. It abutsagainst the friction reducing device 22 and retains it in place in thefitting 10.

The swivel housing 12 is rotatable relative to the depressor 16, thefront housing 14, the biasing member 18, the rear housing 20, and aportion of the friction reducing device 22.

FIGS. 9 and 10 illustrate another embodiment of the friction reducingdevice. In accordance with certain embodiments, the friction reducingdevice 222 of FIGS. 9 and 10 is a needle roller bearing 221, made ofstainless steel, for example, sandwiched by downstream washer 261 andupstream washer 263. The washers 261 and 263 can be made of plastic. Incertain embodiments, the needle rollers are equally spaced by means of acage whose web section separates the rollers and provides guidance tokeep them tracking in an orbital path. It transmits thrust loads betweentwo relatively rotating objects while reducing friction.

FIGS. 11 and 12 illustrate another embodiment of the friction reducingdevice. In accordance with certain embodiments, the friction reducingdevice 322 of FIGS. 10 and 11 is a thrust bearing washer 321, made ofplastic, for example, sandwiched by downstream washer 361 and upstreamwasher 363. The washers 361 and 363 also can be made of plastic.

In operation in certain embodiments, the fitting 10 is coupled to a hoseor the like which is connected to an access fitting on the unit beingserviced or the refrigerant source (or a vacuum pump) and whose otherend is connected to a refrigerant charging manifold. In certainembodiments, the connection to the access fitting (or refrigerant sourceor vacuum pump), for example, is connected via internal threads in theswivel housing 12 that mate with an access fitting containing a Shradervalve (not shown) or the like. The Shrader valved access fitting or thelike has a pin that contacts and depresses depressor 16 against theforce of biasing member 18, moving the depressor 16 axially in adirection away from the access fitting, opening both the fitting 10 andthe Shrader valve to create fluid communication between the hose and theunit being serviced. This axial movement opens a passageway between theperimeter of depressor 16 and the front housing 14 and distal end ofrear housing 20, allowing fluid to flow from the manifold through thefitting and into the hose or the like (not shown) attached to thefitting at the proximal end of rear housing. When the operation iscomplete, removal of the fitting from the high pressure connection canbe carried out by manual rotation of the swivel housing 12, due to thepresence of the friction reducing device 22, 222, 322 which causes thedepressor 16 to move axially way from the access fitting. The force ofthe biasing member 18 then causes the depressor 16 to move axiallytowards the proximal end of the swivel housing 12, closing thepassageway and blocking the flow of fluid.

In certain embodiments, a Shrader valve is not necessary; theanti-blowback valve can be attached directly to a standard accessfitting provided the fitting is shaped to depress the depressor axiallywhen in the assembled condition.

The fitting disclosed herein reduces the torque required to remove itfrom connections under virtually any amount of pressure, and isespecially advantageous the higher the pressure is. For example, atpressures of 500 psi, anti-blowback fittings with the friction reducingdevice required about 20% less torque (as measured with a torque wrench(inch-pounds)) to remove it from a connection than a conventionalanti-blowback fitting devoid of a friction reducing device. At pressuresof 600 psi, anti-blowback fittings with the friction reducing devicerequired about 25% less torque (as measured with a torque wrench(inch-pounds)) to remove it from a connection than a conventionalanti-blowback fitting devoid of a friction reducing device.

What is claimed is:
 1. A fitting, comprising a housing adapted toconnect to a high pressure unit, a depressor in said housing moveableaxially therein between an open and closed position, a biasing member insaid housing biasing said depressor into said closed position, and afriction reducing member in said housing enabling rotation of saidhousing to disconnect said fitting from said high pressure unitmanually.
 2. The fitting of claim 1, wherein said friction reducingmember comprises a thrust bearing.
 3. The fitting of claim 1, whereinsaid friction reducing member comprises a thrust ball bearing.
 4. Thefitting of claim 1, wherein said friction reducing device comprises aneedle roller bearing.
 5. The fitting of claim 1, wherein said frictionreducing device comprises a washer.
 6. The fitting of claim 1, furthercomprising a housing comprising at least one barb for connection to ahose.
 7. The fitting of claim 1, wherein said depressor comprises ahexagonally-shaped base.
 8. A fitting comprising an outer housing, afront housing in said outer housing, a rear housing coupled to saidfront housing, a depressor movable in said outer housing between an openand a closed position, a biasing member in said outer housing biasingsaid depressor to said closed position, a friction reducing device insaid outer housing, and a retaining member in said outer housingsecuring said friction reducing device in said outer housing, whereinsaid outer housing is rotatable relative to said front housing and saidrear housing to couple and decouple said fitting to a high pressureconnection.
 9. The fitting of claim 8, wherein said friction reducingdevice comprises an upstream portion and a downstream portion, andwherein said outer housing is rotatable relative to said downstreamportion.
 10. The fitting of claim 8, wherein said friction reducingdevice comprises a thrust bearing.
 11. The fitting of claim 8, whereinsaid friction reducing device comprises a thrust ball bearing.
 12. Thefitting of claim 8, wherein said depressor comprises ahexagonally-shaped base.